Once upon a time, there was a factory in the Soviet Union that made nails. Moscow set quotas on nail production. When the quotas involved quantity, the factory churned out many small, useless nails. When Moscow realised its error and set a quota by weight instead, the factory produced big, equally useless nails that weighed a pound each.

This much repeated tale of Soviet industrial inefficiency is an urban legend. But it contains a large grain of truth. Communism failed in large measure because central planners had inadequate knowledge of conditions on the ground and their attempts at control were generally thwarted. It would be nice to think that we have learnt from the mistakes of Stalin’s Russia. This is not the case as Jerry Muller explains in his book, “The Tyranny of Metrics.” The world remains in thrall to what Muller calls “metric mania.”